This invention relates to upright floor vacuum cleaners. Upright carpet vacuum cleaners typically employ a rotating cylindrical brush to loosen dirt particles from carpet fibers and allow the dirt to move into the air flow stream for entrainment of dirt into an air duct and ultimately to a dirt receptacle, and to lift the carpet pile for appearance and longer life and to assist the flow of air.
It is known that such cleaners have difficulty picking up grains of sand, and also larger debris such as ice melt, salt pellets and pea rocks, all of which are often found in commercial buildings, especially during the winter. Grains of sand tend to bounce erratically off the cleaner brush, to remain behind the moving cleaner. Consequently the vacuum cleaner must be operated back and forth many times in the same area in efforts to gather such materials off the floor. Prior art upright carpet cleaners of the assignee herein included those having a cylindrical brush with helical bristles oriented in opposite helical directions from the brush ends, a suction nozzle, and an elongated structural portion generally normal to the brush, extending along the brush at a substantial fraction of an inch from the brush.